Safety Assessment of Aircraft Fuel Tank Access Cover under the Impact Load by Tire Fragments

According to relevant airworthiness standards, the aircraft fuel tank access cover must withstand the impact by tire fragments, and minimize the penetration and deformation, which is critical for flight safety. To assess the safety of an aircraft fuel tank access cover subjected to tire fragments, a study of dynamic response was presented in this paper using the Finite element(FE) software ANSYS/LS-DYNA. To obtain the reliable mechanical characteristics of tire tread rubber, a series of material tests have been conducted. Then the proposed rubber material model is validated by comparing the numerical simulations with the experimental results of aluminium alloy plate impact. The simulation results indicate that the rubber fragment and alloy plate will undergo the largest deformation when impact angle is equal to 90°. Finally, the proposed FE model and modelling approaches are extended to the numerical simulation of a full-scale aircraft fuel tank access cover impact. The numerical simulations are carried out with impact velocity of 71.1 m/s and impact angle of 40.5°. The simulation results indicate that the aluminium alloy by precision casting is more likely to rupture, and the middle region of the access cover is vulnerable to fragment impact. This research proposes a reliable rubber model applying to various strain rates. Considering the influence of impact regions, the dynamic response and various failure patterns of fuel tank access cover are acquired. The findings of this paper can be used to improve the future aircraft safety design.

Three-dimensional (3D) hydrogel serves as a platform to identify potential markers of chondrocyte dedifferentiation by combining RNA sequencing

Dedifferentiation of chondrocyte greatly restricts its function and application,however,it is poorly understood except a small number of canonical markers.The non-cell-adhesive property endows polysaccharide hydrogel with the ability to maintain chondrocyte phenotype,which can serve as a platform to identify new molecular markers and therapeutic targets of chondrocyte dedifferentiation.In this study,the high-throughput RNA sequencing(RNA-seq)was first performed on articular chondrocytes at primary(P0)and passage 1(P1)stages to explore the global alteration of gene expression along with chondrocyte dedifferentiation.Significantly,several potential marker genes,such as PFKFB3,KDM6B,had been identified via comparatively analyzing their expression in P0 and P1 chondrocytes as well as in 3D constructs(i.e.chondrocyte-laden alginate hydrogel and HA-MA hydrogel)at both mRNA and protein level.Besides,the changes in cellular morphology and enriched pathway of differentially expressed genes during chondrocyte dedifferentiation was studied in detail.This study developed the use of hydrogel as a platform to investigate chondrocyte dedifferentiation;the results provided new molecular markers and potential therapeutic targets of chondrocyte dedifferentiation.